This invention relates generally to a flexible packaging film construction that contains a biaxially oriented polyester film, an adhesive and a flexible polyamide-containing coextruded film. In addition, this invention relates to a package prepared from a biaxially oriented polyester film, an adhesive and a flexible polyamide-containing coextruded film.
It is common practice to package articles such as food products in multilayer films or laminates to protect the packaged product from abuse and exterior contamination. The multilayer films or laminates provide convenient and durable packages for transportation and ultimate sale to the end user.
It is usual to include printed indicia like decorations and text on packaging films. A desirable aspect of a printed package requires the printed image to repeat identically from one package to the next. This requires the printed image and the package dimensions to coincide exactly over many iterations. When this successfully occurs, the print is deemed to be in register. It is convenient to include a dimensionally stable film like biaxially oriented polyester in the construction of a printed package. Such a film resists elongation through the various manufacturing processes used to produce a film construction and finished package. This resistance to elongation greatly benefits registration control.
Certain package styles are created by a technique known as thermoforming. In this instance, the film is shaped into a cavity by softening the film via thermal exposure and drawing the softened film into a mold. This package style is commonly used to contain items like processed meat. Film constructions engineered to accommodate thermoforming do not often include biaxially oriented films. The resistance to elongation of biaxially oriented films makes them especially difficult to thermoform. Beyond the formation of very shallow cavities, thermoformed articles that include biaxially oriented films tend to encounter defects like holes and poor definition of shape. Still, there exists limited use of oriented films in end uses that require the formation of very shallow cavities. These applications profit from the ability to easily and repetitively print the films such that the indicia on the packages are in register. It is desirable to extend the use of biaxially oriented films to include the manufacture of register printed packages with deeper thermoformed cavities.